JPH08303877A - Air conditioner - Google Patents

Abstract

PURPOSE: To enable adaptation to high and low loads by a method wherein a first shutoff valve is opened while a second shutoff valve is left closed when an air conditioning load and an outside air load are large and a second shutoff valve is opened while the first shutoff valve is left closed when the air conditioning load is small. CONSTITUTION: A controller 28 works to open a first shutoff valve 23 while a second shutoff valve 26 is left closed when an air conditioning load is large (for example, when changeover valves 9 and 10 are opened) and an outside air load is large (for example when outside air temperature is above 3.9 deg.C) and to open the second shutoff valve 26 while the first shutoff value 23 is left closed when the air conditioning load is small (for example when any one is not used among room heat exchangers 30 and 35, or when one is closed among changeover valves 9 and 10). This does not require the use of any costly part such as a variable capacity compressor or an opening adjustable valve thereby making the apparatus inexpensive and adptable to high and low loads as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner provided with a plurality of indoor heat exchangers, which is a so-called multi-type air conditioner.

[0002]

2. Description of the Related Art An example of an air conditioner for cooling a room is disclosed in Japanese Patent Publication No. 50-34343. Such an air conditioner includes a refrigeration cycle in which a compressor, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger are connected by a refrigerant pipe.

[0003]

Some of the above-mentioned air conditioners are provided with a plurality of indoor heat exchangers, for example, two in parallel, and such an air conditioner is called a so-called multi-type air conditioner. There is. In such an air conditioner, the circulation amount of the refrigerant differs between the case where only one indoor heat exchanger is used (low load) and the case where both of them are used. A quantity controlling arrangement, eg a receiver tank, must be installed. Also, if it is not possible to cope with a large load such as when the temperature of the outdoor air is high, the protection device of the air conditioner may operate and the operation of the air conditioner may stop halfway. is there. However, when a compressor driven at a constant speed is used in order to reduce the price, the drive speed of the compressor cannot be controlled. Therefore, in order to configure to correspond to the low load and the high load, Very difficult.

The present invention provides an inexpensive air conditioner capable of handling high loads and low loads.

[0005]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a plurality of indoor heat exchangers arranged in parallel with a compressor operated at a constant speed, an outdoor heat exchanger, and a pressure reducing device. In an air conditioner in which a compressor and a compressor are connected by a refrigerant pipe, a pipe on the outlet side of the outdoor heat exchanger and a pipe on the suction side of the compressor are
While connecting with a bypass pipe, a first opening / closing valve and a first pressure reducer are provided in this pipe, and a pipe on the discharge side of the compressor and a pipe on the suction side of the compressor are connected with a second bypass pipe, and The pipe is provided with a second on-off valve and a second decompressor, and when the air-conditioning load and the outside air load are large, the first on-off valve is opened, and
The second opening / closing valve is kept closed, and when the air conditioning load is small, the first opening / closing valve is kept closed and a control device for opening the second opening / closing valve is provided.

In a second aspect of the invention, the first and second pressure reducing devices in the first aspect of the invention are composed of first and second capillary tubes.

In a third aspect of the present invention, a compressor operated at a constant speed, an outdoor heat exchanger, and a plurality of indoor heat exchangers arranged in parallel with a pressure reducing device are connected by a refrigerant pipe, and each heat exchanger is connected. In an air conditioner equipped with respective switching valves for stopping the flow of refrigerant to the outside and an outside air temperature detector for detecting the temperature of outdoor air, a pipe on the outlet side of the outdoor heat exchanger and a suction side of the compressor. The first bypass pipe and the first on-off valve and the first decompressor are provided in the pipe, and the discharge side pipe of the compressor and the suction side pipe of the compressor are connected to the second bypass pipe. While connecting with a pipe, a second on-off valve and a second pressure reducer are provided in this pipe,
When the switching valves are all open and the temperature detected by the outside air temperature detector is higher than a predetermined temperature, the first opening / closing valve is opened and the second opening / closing valve is kept closed, When some of the control valves are closed, the first opening / closing valve is kept closed and a control device for opening the second opening / closing valve is provided.

[0008]

According to the first and second aspects of the invention, when the air conditioning load and the outside air load are large, the first opening / closing valve is opened and the liquid refrigerant is guided to the suction side pipe of the compressor. The side pipe and the refrigerant are cooled by the evaporation of the liquid refrigerant, and the temperature rise of the refrigerant is prevented. Further, when the air conditioning load is small, there is excess refrigerant, so this excess refrigerant is guided to the compressor without passing through the outdoor heat exchanger, so that the refrigerant flowing to the indoor heat exchanger used does not become excessive. And the circulation amount of the refrigerant is adjusted.

In particular, in the second invention, since capillary tubes are used as the first and second pressure reducing devices of the first invention, it is easy to adjust the resistance of the first and second bypass pipes. In addition, the decompression device can be constructed at low cost.

According to the third aspect of the present invention, when the air conditioning load is large such that all the switching valves are opened and the outside air temperature is large such that the outside air temperature is equal to or higher than a predetermined temperature, the first and second aspects are provided.
Since the first on-off valve is opened similarly to the invention of 1, the temperature rise of the refrigerant is prevented. Further, when the air conditioning load is small, such as when there is an indoor heat exchanger through which the refrigerant does not flow, such as some of the switching valves being closed, the second opening / closing operation is performed as in the first and second inventions. The valve is opened and the circulation amount of the refrigerant is adjusted.

[0011]

Embodiments of the present invention will be described with reference to the drawings.
Reference numeral 1 denotes a separation type air conditioner, which is mainly composed of an outdoor unit 2, an inter-unit pipe 3, and indoor units 4, 5 arranged in different rooms. Moreover, since this air conditioner includes a plurality of indoor units, it is also called a multi-type air conditioner.

The outdoor unit 2 includes a compressor 6 for compressing a refrigerant, an outdoor heat exchanger 7, a pressure reducing device 8 using a capillary tube, switching valves 9 and 10 using on-off valves, mufflers 11 and 12, Auxiliary depressurizers 13 and 14, service valves 15 and 16, service valves 17 and 18, muffler 19, and accumulator 20 using capillary tubes.
Is stored. 21A, 21B, 21C, 21D,
Reference numerals 21E, 21F, 21G, 21H, and 21I are refrigerant pipes for connecting these devices. Reference numeral 22 denotes a first bypass pipe connecting the refrigerant pipe 21B and the refrigerant pipe 21I, and a first opening / closing valve 23 and a capillary tube (first pressure reducer) in the middle thereof.
And 24 are provided. A second bypass pipe 25 is provided with a second opening / closing valve 26 and a capillary tube (second pressure reducer) 27 in the middle thereof. A control device 28 controls the first and second on-off valves 23 and 25. The control device 28 controls each device of the outdoor unit by transmitting and receiving a signal from a control device (not shown) of the indoor unit. 29 is arranged on the suction side of the outdoor heat exchanger and is for detecting the air temperature on the suction side of this heat exchanger (the temperature of the outdoor air, so-called outside air temperature).

The outdoor unit 2 is provided with a blower for guiding outdoor air to the outdoor heat exchanger 7, but it is not shown.
Further, the indoor units 4 and 5 are also provided with a blower for guiding the indoor air to the indoor heat exchanger, but they are not shown.

The indoor unit 4 is provided with an indoor heat exchanger 30, auxiliary refrigerant pipes 31, 32, and connecting portions 33, 34. Similarly, the indoor unit 5 includes an indoor heat exchanger 35, and an auxiliary refrigerant pipe 3
6, 37, and connecting portions 38, 39.

The inter-unit pipe 3 is composed of pipes 40, 41, 4
2 and 43, and tubes 42 and 43 are tubes 40 and 4,
It uses a tube slightly thicker than 1.

The outdoor control device 28 and the indoor control device (not shown) are connected by a unit pipe cable, but they are not shown.

The control device 28 operates when the air conditioning load is large (for example, when the switching valves 9 and 10 are open).
Moreover, when the outside air load is large (for example, when the outside air temperature is 39 ° C. or higher), the first opening / closing valve 23 is opened and the second opening / closing valve 2 is opened.
It keeps 6 closed. In addition, the control device 28 controls when the air conditioning load is small (for example, the indoor heat exchanger 3).
0, 35 when there is an unused heat exchanger, that is, when one of the switching valves 9, 10 is closed), the second opening / closing valve 26 is opened and the first opening / closing valve 23 is kept closed. It is something to do.

Further, in this air conditioner, the tubes 40, 4
Even when the length dimension of 1, 42, 43 is long, the refrigerant is overcharged so that it is not necessary to charge the additional refrigerant. For example, if the total length of the tubes 40 and 41 is up to 30 m, or if the length of the tubes 40 or 41 is up to 20 m, the refrigerant is charged so that additional refrigerant charging may not be performed. .

This air conditioner does not have a receiver tank for storing excess refrigerant. For this reason, the outdoor heat exchanger 7 is configured as a slightly larger heat exchanger so that the excess refrigerant can be stored. The capillary tubes 24 and 27 are for adjusting the circulation amount of the refrigerant and for maintaining a pressure difference.

In the air conditioner 1 thus constructed,
Cooling operation is possible, but heating operation is not possible because it does not have a four-way valve.

When one of the indoor units is used, for example, only the indoor unit 4 is used, the control device opens the control valve 10 and closes the control valve 9. Further, the opening / closing valve 23 is closed and the opening / closing valve 26 is opened. When the compressor 6 is operated in such a valve state, about 70 to 80% of the refrigerant flows to the outdoor heat exchanger 7, the pressure is reduced by the capillary tubes 8 and 14, and the refrigerant flows to the indoor heat exchanger 30. The refrigerant flows in, the heat of the indoor air is taken by the refrigerant, and the room is cooled. Further, about 20 to 30% of the refrigerant flows through the second bypass pipe 25 to the refrigerant pipe 21I. In this way, when only one indoor heat exchanger is used (when the load is low), some of the refrigerant is idled without being used, so the amount of refrigerant that is suitable for this low load operation Is adjusted to. Therefore, the indoor heat exchanger is prevented from freezing.

When both indoor units 4 and 5 are used, the compressor 6 is operated with the valves 9 and 10 opened and the on-off valves 23 and 26 closed. When the compressor 6 is operated, the refrigerant discharged from the compressor 6 passes through the outdoor heat exchanger 7 and is then divided into the pipes 21D and 21E, and flows into the indoor heat exchangers 35 and 30, respectively, to flow inside the room. To cool.

When the outside air temperature rises and the outside air temperature reaches 39 ° C. (predetermined temperature) or above in a state where the two indoor units 4 and 5 are operated as described above, the control device 28 is under high load. It is judged that there is, and the on-off valve 23 is opened. When the opening / closing valve 23 is opened, a part (about 5%) of the liquid refrigerant is guided from the compressor 6 to the pipe 21I. The liquid refrigerant introduced to the pipe 21I evaporates and cools the pipe 21I (a temperature of about 8 ° C. can be lowered with a refrigerant amount of about 5%). Along with this cooling, the refrigerant on the suction side is also cooled. Part of liquid refrigerant is pipe 2
When it is led to 1I, the cooling capacity of the indoor heat exchanger is slightly reduced, but a protective device for stopping the operation, for example, an overload relay (not shown) for stopping the operation when the temperature of the heat exchanger becomes 110 ° C or higher. It is possible to continue the operation while preventing the discomfort that the cooling operation becomes discontinuous because the operation of (1) is suppressed. Therefore, even on a hot summer day, the operation can be continued without stopping the cooling operation.

Moreover, since this air conditioner does not use expensive parts such as a variable capacity compressor and a valve whose opening can be adjusted, the cost of the air conditioner can be reduced.

[0025]

According to the first, second and third aspects of the present invention, when the air conditioning load is large and the outside air load is large, the first
The on-off valve is opened, the suction side pipe of the compressor and the refrigerant are cooled by the evaporation of the liquid refrigerant to prevent the temperature of the refrigerant from rising, and when the air conditioning load is small, the second on-off valve opens. As a result, a part of the refrigerant is guided to the compressor without passing through the outdoor heat exchanger, so that the circulation amount of the refrigerant is adjusted. Moreover, this air conditioner does not use expensive parts such as variable capacity compressors and valves with adjustable opening.
The cost of the air conditioner can be reduced, and it is possible to cope with both high and low loads.

Particularly, in the second invention, the first and second
Since a capillary tube is used as the decompression device of the above, it is easy to adjust the resistance of the first and second bypass pipes,
Moreover, since the decompression device can be constructed at low cost, the air conditioner can be made inexpensive and the design can be facilitated.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing an air conditioner of the present invention.

[Explanation of symbols]

 1 Air conditioner 6 Compressor 7 Outdoor heat exchanger 8 Pressure reducing device 9 Switching valve 10 Switching valve 22 First bypass pipe 23 First opening / closing valve 24 Capillary tube (first pressure reducing device) 25 Second bypass pipe 26 Second opening / closing valve 27 Capillary Tube (Second Decompressor) 28 Control Device 30 Indoor Heat Exchanger 35 Indoor Heat Exchanger

Claims (3)

[Claims] 1. An air conditioner in which a compressor operated at a constant speed, an outdoor heat exchanger, and a plurality of indoor heat exchangers arranged in parallel with a pressure reducing device are connected by a refrigerant pipe, wherein the outdoor heat exchanger is used. A pipe on the outlet side and a pipe on the suction side of the compressor are connected by a first bypass pipe, and a first opening / closing valve and a first pressure reducer are provided on this pipe, and the pipe on the discharge side of the compressor is compressed. A second bypass pipe is connected to the suction side pipe of the machine, and a second opening / closing valve and a second decompressor are provided in this pipe, and the first opening / closing valve is opened when the air conditioning load and the outside air load are large. With the second
An air conditioner comprising: a control device that keeps the on-off valve closed, keeps the first on-off valve closed when the air conditioning load is small, and opens the second on-off valve. 2. An air conditioner in which a compressor operated at a constant speed, an outdoor heat exchanger, and a plurality of indoor heat exchangers arranged in parallel with a pressure reducing device are connected by a refrigerant pipe, wherein the outdoor heat exchanger is used. A pipe on the outlet side and a pipe on the suction side of the compressor are connected by a first bypass pipe, and a first opening / closing valve and a first capillary tube are provided on this pipe, and the pipe on the discharge side of the compressor is compressed. A second bypass pipe is connected to the suction side pipe of the machine, and a second opening / closing valve and a second capillary tube are provided in this pipe, and the first opening / closing valve is opened when the air conditioning load and the outside air load are large. At the same time, the air is provided with a control device that keeps the second on-off valve closed and closes the first on-off valve when the air conditioning load is small and keeps the second on-off valve open. Harmony machine. 3. A compressor operating at a constant speed, an outdoor heat exchanger, and a plurality of indoor heat exchangers arranged in parallel with a decompression device are connected by refrigerant pipes, and refrigerant for each heat exchanger is connected. In an air conditioner equipped with respective switching valves for stopping the flow and an outside air temperature detector for detecting the temperature of outdoor air, a pipe on the outlet side of the outdoor heat exchanger and a pipe on the suction side of the compressor are provided. While connecting with a first bypass pipe, a first opening / closing valve and a first pressure reducer are provided in this pipe, and a pipe on the discharge side of the compressor and a pipe on the suction side of the compressor are connected with a second bypass pipe. The pipe is provided with a second on-off valve and a second pressure reducer, all the switching valves are opened, and when the temperature detected by the outside air temperature detector is higher than a predetermined temperature, 1 Opening the on-off valve, keeping the second on-off valve closed, and closing the control valve An air conditioner comprising a control device for opening the second on-off valve while keeping the first on-off valve closed when there is an item.